Flow guide structure

Abstract

Rotary pump (1) for pumping a fluid, the rotary pump (1) comprising (a) a pump housing (2) with a low-pressure inlet (3) and a high-pressure outlet (4) for the fluid to be pumped, (b) a pumping rotor (5) rotatably arranged in the pump housing (3) about an axis of rotation (D) with (c) several pumping means (5a) distributed around the circumference of the pumping rotor (5) for pumping the fluid from the low-pressure inlet (3) to the high-pressure outlet (4), wherein (d) the pumping means (5a) with their radial and axial outer edges define a pumping area (6) of the rotary pump (1) when the pumping rotor (5) rotates, and (e) the rotary pump (1) has a flow guide structure (10) projecting axially into the low-pressure inlet (3) with respect to the axis of rotation (D), which is designed to influence, preferably to change the direction of, the fluid flowing in the low-pressure inlet (3),wherein (f) the flow guide structure (10) is arranged axially next to the conveying area (6) and overlaps at least section by section with the conveying area (6) in the radial direction, and wherein (g) the flow guide structure (10) has a leading edge (14) which is spaced radially away from the conveying area (6) and is arranged substantially parallel to the axis of rotation D.

Description

The invention relates to a rotary pump for pumping a fluid. The rotary pump can be, for example, a vane pump or a gear pump, in particular an internal gear pump. The rotary pump comprises a pump housing with a low-pressure inlet and a high-pressure outlet. A pumping rotor, rotatable about an axis of rotation, is arranged inside the pump housing. The pumping rotor has several conveying elements distributed around its circumference, designed to convey the fluid to be pumped from the low-pressure inlet to the high-pressure outlet during operation of the rotary pump. When the pumping rotor rotates, the axial and radial outer dimensions of the conveying elements define a pumping range for the rotary pump. Furthermore, the rotary pump has a flow guide structure arranged in the low-pressure inlet.The flow guide structure is designed to influence the fluid flowing in the low-pressure inlet, in particular to change its direction. Rotary pumps are known in the prior art in which the pumping area is supplied axially and / or radially with the fluid to be pumped from the low-pressure inlet. The fluid to be pumped flows axially and / or radially from the low-pressure inlet into a low-pressure section of the pumping area. For example, DE 102 33 582 A1 discloses a rotary pump with a low-pressure inlet that divides into two branch channels for supplying the pumping area, and the fluid to be pumped is supplied axially and radially to a low-pressure section of the pumping area. To generate an irrotation-free flow, DE 102 33 582 A1 provides flow-guiding means in the axial end faces of the pump housing. US 10,753,358 B2, however, discloses a pump with a low-pressure inlet having two branch channels that meet in a connecting section with a flow-guiding structure. For flow control in the low-pressure inlet of the pump, DE 102 54 220 A1 and DE 10 2011 084 405 A1 provide for a nozzle-shaped insert in the low-pressure inlet. DE 10 2005 027 607 A1, however, teaches the use of an outlet valve for the outlet of the first working flow of a double-stroke pump, the valve tongue of which can act as a flow guide to direct the fluid to the inlet of the second working flow. In the direction of rotation of the pump rotor, filling with the fluid to be pumped is regularly limited, particularly at the beginning and towards the end of the low-pressure range. This is because the fluid flowing in the low-pressure inlet has only one main flow direction, namely a flow direction determined by the design of the low-pressure inlet. As a result, the low-pressure range is only optimally supplied with the fluid to be pumped in a portion of it. This undesirable effect negatively impacts the pumping performance of known rotary pumps. It is an object of the invention to provide a rotary pump that has improved pumping characteristics and is also inexpensive to manufacture. This problem is solved using the features of claim 1. Advantageous further developments result from the dependent claims, the description, and the figures. The rotary pump according to the invention is designed for pumping a fluid. The rotary pump can be, for example, a vane pump or a gear pump, in particular an internal gear pump. The rotary pump comprises a pump housing with a low-pressure inlet and a high-pressure outlet. Preferably, the fluid to be pumped flows into the pump housing via the low-pressure inlet and out of the pump housing via the high-pressure outlet. The pump housing can be multi-part, preferably two-part. For example, the pump housing can comprise a housing cover and a housing bowl. In such an embodiment, the low-pressure inlet and / or the high-pressure outlet can be substantially limited by the housing bowl. That is, the housing cover preferably limits the low-pressure inlet and / or the high-pressure outlet only on one side, partially, or not at all. A pump rotor is arranged within the pump housing. The pump rotor is rotatable about an axis of rotation. Several pumping elements are distributed around the circumference of the pump rotor. These pumping elements are preferably distributed at equal intervals around the circumference of the pump rotor. Alternatively or additionally, the pumping elements can also have varying distances from each other in the circumferential direction. The pumping elements are designed to convey the fluid to be pumped from the low-pressure inlet to the high-pressure outlet. If the rotary pump is, for example, a vane pump, the pumping elements can be formed by movable vanes. The movable vanes can be arranged to be displaceable within a rotor body of the pump rotor, or, alternatively, to be pivotable. Displaceable vanes can be extended and retracted with a radial component relative to the axis of rotation.If the rotary pump is, for example, a gear pump, the pumped medium can be formed by the teeth of a pumping gear. Preferably, the impeller is arranged axially between two end faces of the pump housing. If the pump housing is multi-part, particularly two-part, the housing cover can have a first end face and the housing tub a second end face. For example, the impeller is arranged axially between the first and second end faces. In such an embodiment, the impeller can be axially limited on one side by the housing cover. The housing tub can also axially limit and enclose the impeller on one side. In other words, the impeller can be axially limited on one side and radially limited by the housing tub. This advantageously allows the impeller to be inserted into the housing tub during the manufacture of the rotary pump, and the rotary pump to be easily closed by attaching the housing cover. This ensures cost-effective manufacturing of the rotary pump.When the pump rotor rotates, particularly during operation of the rotary pump, the pumping elements, with their radial and axial outer edges, define a pumping range. In other words, the pumping range can be defined by the integral of the pumping area of ​​a pumping element over one revolution of the pump rotor. The pumping area is the surface of a pumping element that is in circumferential contact with the fluid being pumped, or that actually pumps the fluid. If the rotary pump is, for example, a vane pump with movable vanes in a rotor body, the pumping range is defined axially by the axial extent of the vanes. Radially, the pumping range preferably extends from the outer surface of the rotor body to a circumferential surface that limits the radial movement of the vanes outwards (away from the axis of rotation).This can be, in particular, an inner surface of the pump housing or an inner surface of an actuating element. The latter is preferably the case if the vane pump has an adjustable delivery volume. The low-pressure inlet of the rotary pump can extend from a fluid connection on the outside of the pump housing to the pumping area. Preferably, the low-pressure inlet is limited by the pump housing. With respect to the axis of rotation of the pump rotor, the low-pressure inlet extends, for example, radially and / or tangentially into the pump housing. This has the advantageous effect that the rotary pump can be designed very compactly and, in particular, can have small axial dimensions. The fluid flowing through the low-pressure inlet can have a main flow direction that is essentially orthogonal to the axis of rotation of the conveying rotor. "Essentially" here means a deviation of ≤ ±20°. Preferably, the low-pressure inlet does not extend in the axial direction. The rotary pump according to the invention comprises a flow guide structure arranged in the low-pressure inlet. The flow guide structure is designed to influence the fluid flowing in the low-pressure inlet. Preferably, only a portion of the fluid flowing in the low-pressure inlet is directly influenced by the flow guide structure. The term "influence" is understood to mean, in particular, a change in direction, acceleration, and / or deceleration of the fluid. The flow guide structure is positioned in the low-pressure inlet such that it projects axially into the low-pressure inlet with respect to the axis of rotation of the pump rotor. For example, the flow guide structure projects axially into the low-pressure inlet from a wall of the pump housing that may define the low-pressure inlet. The flow guide structure can be formed integrally with the pump housing, particularly by being pre-molded with the pump housing in one piece. If the pump housing is multi-part, particularly in two parts, the flow guide structure can be formed integrally with the housing shell, particularly by being pre-molded with the housing shell in one piece. Alternatively, the flow guide structure can be a component of the rotary pump that is attached to the housing, particularly to the housing shell. Preferably, the flow guide structure is completely contained within the housing shell. In other words, the flow guide structure does not project axially or radially from the housing shell or beyond its outer dimensions. In a further exemplary embodiment, both the low-pressure inlet and the flow guide structure are located within the housing shell.In such an embodiment, the rotary pump can be manufactured cost-effectively and / or has small dimensions, in particular small axial dimensions. The flow guide structure is arranged axially adjacent to the conveying area. Preferably, the flow guide structure extends completely axially adjacent to the conveying area. In the radial direction, the flow guide structure overlaps the conveying area at least partially. This has the technical advantage that the fluid flowing in the low-pressure inlet can also be influenced axially adjacent to the conveying area by the flow guide structure. In one exemplary embodiment, the flow guide structure can have a first section extending radially, which overlaps the conveying area. Furthermore, the flow guide structure can have a second section that does not overlap the conveying area radially, but is preferably located radially adjacent to it. The second section is preferably also axially adjacent to the conveying area, but in alternative embodiments, it can also overlap axially with it. For example, it is conceivable that the second section of the flow guide structure extends axially through the entire low-pressure inlet and, for instance, divides it.Independently of this, the second section of the flow guide structure, which does not radially overlap with the conveying area, can extend axially over less than 75%, preferably less than 50%, of the axial extent of the conveying area, particularly the low-pressure area. Advantageously, the second section adjoins the first section directly in the radial direction, particularly from radially inward to radially outward. The flow guide structure preferably tapers in the opposite direction to the fluid flow. In other words, the circumferential width of the flow guide structure can increase in the direction of flow. Advantageously, the flow guide structure is exposed to the fluid flow from a radial and / or tangential direction relative to the axis of rotation of the pump rotor. However, the flow guide structure is not exposed to the fluid flow from an axial direction. This advantageously allows for a low overall height of the rotary pump. The flow-guiding structure has a leading edge. The term "leading edge" refers to an edge of the flow-guiding structure facing the oncoming fluid. Preferably, the leading edge is the first structure of the flow-guiding system to come into contact with the oncoming fluid. Advantageously, the stagnation point of the flow-guiding structure is located on the outer circumference of the leading edge. The leading edge is radially spaced from the conveying area. Axially, the leading edge extends alongside the conveying area and / or projects into an axial overlap with the conveying area. Regardless of this, the leading edge is arranged substantially parallel to the axis of rotation of the conveying rotor. "Substantially" here means a deviation of ≤ ±10°. Preferably, the flow-guiding structure is circumferentially bounded by a side wall on each side. The side walls can extend parallel to each other in the axial direction. For example, both side walls can extend substantially parallel to the axis of rotation of the conveying rotor in the axial direction. "Substantially" here means a deviation of ≤ ±10°. Alternatively, the side walls can converge and / or diverge from each other in the axial direction, particularly in sections. Preferably, the side walls extend in a straight line in the axial direction. Alternatively or additionally, the side walls can each have concave and / or convex sections in the axial direction. The side walls can extend radially from the leading edge to the radial overlap with the conveying area.Preferably, the side walls extend radially to the end face of the pump housing. For example, the side walls can extend radially to the end face of the housing shell. The circumferential distance between the side walls can increase in the direction of fluid flow. Preferably, the two side walls have a maximum circumferential distance in the radial overlap with the conveying area. Independently of this, the maximum circumferential distance between the two side walls can be smaller than the maximum circumferential distance between any two outer conveying elements out of a total of three adjacent conveying elements. Alternatively or additionally, the maximum circumferential distance between the two side walls can be larger than the maximum circumferential distance between any two adjacent conveying elements. A first side wall of the flow guide structure is preferably designed to influence the direction of the fluid flowing along it. Preferably, the fluid flowing along the first side wall is directed in a direction opposite to the direction of rotation of the pump rotor. In an exemplary embodiment, the first side wall of the flow guide structure, together with a wall of the pump housing, in particular with a wall of the pump housing that delimits the low-pressure inlet, can form a first partial inlet channel. The first partial inlet channel is, in particular, open axially on one side. This means that fluid communication is possible between the fluid flowing in the first partial inlet channel and the fluid flowing in the remaining low-pressure inlet. A partial flow of the fluid to be pumped, flowing in the first partial inlet channel, is influenced by the first partial inlet channel.In particular, the direction and / or velocity of the partial flow passing through the first partial inlet channel can be influenced. For example, the partial flow passing through the first partial inlet channel can be directed in a direction opposite to the direction of rotation of the conveyor rotor. Alternatively or additionally, the first partial inlet channel can have a cross-section that tapers in the direction of flow. This can result in an advantageous acceleration of the partial flow passing through the first partial inlet channel. A second side wall of the flow guide structure is preferably designed to influence the direction of the fluid flowing along it. Preferably, the fluid flowing along the second side wall is directed in a direction corresponding to the direction of rotation of the pump rotor. In an exemplary embodiment, the second side wall of the flow guide structure, together with a wall of the pump housing, in particular with a wall of the pump housing that delimits the low-pressure inlet, can form a second partial inlet channel. The second partial inlet channel is, in particular, open axially on one side. This means that fluid communication is possible between the fluid flowing in the second partial inlet channel and the fluid flowing in the remaining low-pressure inlet. A partial flow of the fluid to be pumped, flowing in the second partial inlet channel, is influenced by the second partial inlet channel.In particular, the direction and / or velocity of the partial flow passing through the second partial inlet channel can be influenced by this channel. For example, the partial flow passing through the second partial inlet channel can be directed in a direction corresponding to the direction of rotation of the conveyor rotor. Alternatively or additionally, the second partial inlet channel can have a cross-section that tapers in the direction of flow. This can result in an advantageous acceleration of the partial flow passing through the second partial inlet channel. The flow guide structure can be axially bounded by an axial end wall. The axial end wall can extend at least partially orthogonally to the axis of rotation of the conveying rotor. Alternatively or additionally, the axial end wall can have a convex and / or concave shape, at least partially. Independently of this, the distance measured in the axial direction between the conveying area and the axial end wall can vary, particularly in the radial direction. For example, the axial distance between the conveying area and the axial end wall can be smallest, and in particular minimal, in the first section of the flow guide structure. The axial distance measured in the axial direction between the conveying area and the axial end wall can be largest, and in particular maximal, in the second section. Preferably, the axial end wall has a concave shape in the second section. The skeletal line of the flow guide structure (or flow guide structure centerline) can exhibit a radial curvature. In fluid mechanics, the term "skeletal line" refers here to a line connecting all the centers of the circles inscribed by the profile of the flow guide structure. The profile of the flow guide structure is preferably defined by its outer edges in a cross-sectional view orthogonal to the axis of rotation. Preferably, the skeletal line is curved from radially inward to radially outward with respect to the axis of rotation of the conveying rotor, in the direction of the fluid connection of the low-pressure inlet. This advantageously allows a fluid with a main flow direction radial and / or tangential to the axis of rotation to be deflected by the flow guide structure in such a way as to achieve optimal supply or filling of the conveying area.Regardless of this, a curved skeleton line has the positive technical effect that the design of the rotary pump can be chosen to be particularly variable and especially compact. The first side wall, viewed axially, can be concave, preferably rounded or bulged, to guide the fluid in a direction opposite to the rotation of the conveying rotor. The first side wall preferably faces the fluid flowing towards the flow guide structure. The second side wall, viewed axially, can be convex, preferably rounded or bulged, to guide the fluid so that it is directed towards the conveying area in the direction of rotation of the conveying rotor. Viewed axially, the flow guide structure can have the shape of a shark fin, tapering towards the flowing fluid. The rotary pump can be designed specifically for use in a motor vehicle. Accordingly, the rotary pump can be configured as a motor vehicle pump. The rotary pump is preferably designed for pumping a fluid, in particular a lubricant and / or coolant and / or actuation fluid. Accordingly, the rotary pump can be configured as a fluid pump. The rotary pump is preferably designed for supplying and / or lubricating and / or cooling a motor vehicle engine or a motor vehicle transmission. Preferably, the fluid is an oil, more preferably engine oil or transmission oil. The rotary pump can be configured specifically as an engine lubricant pump for a motor vehicle or as a transmission pump for a motor vehicle. The features described above can be combined with one another as desired, provided this is technically sensible and suitable. Further features, combinations of features, and advantages of the invention will become apparent from the following description of exemplary embodiments with reference to the figures. The figures show: Fig. 1 a first sectional view of an exemplary embodiment of a rotary pump according to the invention, Fig. 2 a perspective view of the sectional view shown in Fig. 1, Fig. 3 a second sectional view of the exemplary embodiment shown in Fig. 1, Fig. 4 a third sectional view of the exemplary embodiment shown in Fig. 1, Fig. 5 a fourth sectional view of the exemplary embodiment shown in Fig. 1, and Fig. 6 a detail of a side view of the exemplary embodiment shown in Fig. 1. Fig. 1 is a sectional view of an embodiment of the rotary pump 1 according to the invention. In this embodiment, the rotary pump 1 is designed as a vane pump. The rotary pump 1 has a pump housing 2, which includes a low-pressure inlet 3 and a high-pressure outlet 4 for the fluid to be pumped. To direct the fluid to be pumped into the interior of the rotary pump 1, the low-pressure inlet 3 has a fluid connection 3a on the outer wall of the pump housing 2. The fluid connection 3a forms an inlet opening for the low-pressure inlet 3, which extends into the pump housing 2. Similarly, the high-pressure outlet 4 has a fluid connection (not shown) to discharge the pumped fluid from the rotary pump 1. A conveying rotor 5 is provided within the pump housing 2, which is rotatable about an axis of rotation D. The conveying rotor 5 is arranged axially between two end faces of the pump housing 2. The conveying rotor 5 comprises a rotor base 5b and several conveying elements 5a. The conveying elements 5a are distributed around the circumference of the rotor base 5b. In the illustrated embodiment, the conveying elements 5a are radially movable with respect to the axis of rotation D and are arranged at equal intervals from one another. The radial movement of the conveying elements 5a inwards (in the direction of the axis of rotation D) is limited by the rotor base 5b. The radial movement of the conveying elements 5a in the opposite direction, i.e., radially outwards (away from the axis of rotation D), is limited by an inner surface 21 of an actuating element 20. In an alternative embodiment not shown, in particular if the rotary pump 1 is designed as an internal gear pump, the conveying rotor 5 could, for example, also be a gear whose teeth form the conveying means 5a. During operation of the rotary pump 1, the pump rotor 5 rotates about the axis of rotation D. The pumped fluids 5a are thereby forced radially outwards towards the inner surface 21 of the actuating element 20 due to the centrifugal force acting upon them. Together with the outer surface 5c of the rotor body 5b and the inner surface 21 of the actuating element 20, the axial outer edges of the pumped fluids 5a define a pumping area 6. The pumping area 6 is thus an annular volume whose axial width corresponds to the width of the pumped fluids 5a. Within the pumping area 6, two adjacent pumped fluids 5a form a pumping cell 7. The pumping area 6, or the pumping cells 7, are supplied with the fluid to be pumped via the low-pressure inlet 3. Within the pumping area 6, the fluid to be pumped is conveyed from the low-pressure inlet 3 to the high-pressure outlet 4.The fluid to be conveyed is conveyed from the low-pressure inlet 3 to the high-pressure outlet 4, particularly within the conveying cells 7 under the direct influence of the rotating conveying means 5a. The actuating element 20 is designed to change or adjust the delivery volume of the rotary pump 1. For this purpose, the actuating element 20 is movable back and forth between at least two positions relative to the pump housing 2. In the exemplary embodiment, the actuating element 20 is translationally movable. This means that the actuating element 20 is arranged so as to be displaceable within the pump housing 2. The inner surface 21 of the actuating element 20 extends around a central axis (not shown), which, in a first position of the actuating element 20, is parallel to the axis of rotation D of the conveying rotor 5. Due to the parallel offset of the central axis of the actuating element 20 relative to the axis of rotation D of the conveying rotor 5, the actuating element 20 exhibits an eccentricity with respect to the conveying rotor 5. Fig. 1 shows the actuating element 20 in the first position. In the first position, the pumping range 6 comprises a low-pressure range 6a, in which the volume of the pumping cells 7 increases in the direction of rotation of the pumping rotor 5. Furthermore, in the first position of the actuating element 20, the pumping range 6 comprises a high-pressure range 6b, which adjoins the low-pressure range 6a in the direction of rotation of the pumping rotor 5. In the high-pressure range 6b, the volume of the pumping cells 7 decreases in the direction of rotation of the pumping rotor 5. The rotary pump 1 has a maximum pumping volume in the first position. In a second position (not shown), the actuating element 20 is displaced within the pump housing 2 such that it exhibits minimal or no eccentricity with respect to the conveying rotor 5. In other words, the central axis of the actuating element 20 is essentially or nearly coaxial with the axis of rotation D of the conveying rotor 5 in this second position. The rotary pump 1 has a minimal delivery volume in this second position. The first and second positions are preferably end positions of the actuating element 20. This means that the actuating element 20 cannot assume a position in which it has a greater eccentricity relative to the conveying rotor 5 than in the first position, and / or that it cannot have a lesser eccentricity relative to the conveying rotor 5 than in the second position. The actuating element 20 can assume several, in particular any number of, intermediate positions between the first and second positions. The rotary pump 1 includes a return element 8 to move the actuator 20 into the first position. Preferably, the return element 8 exerts a return force on the actuator 20, the return force pushing the actuator 20 into the first position. The return element 8 can have at least one return spring 8, which is supported on one side by the pump housing 2 and on the other side by the actuator 20. In the exemplary embodiment, the return element 8 has two return springs 8, which are supported on one side by the pump housing 2 and on the other side by the actuator 20. To move the actuator 20 into the second position, the rotary pump 1 includes a pressure channel 22 and a pressure chamber 23. The pressure chamber 23 extends between the pump housing 2 and the actuator 20. A pressurized fluid can be introduced into the pressure chamber 23 via the pressure channel 22.The fluid pressure prevailing in the pressure chamber 23 acts on the actuating element 20 against the restoring force of the restoring means 8 in the direction towards the second position. The pressurized fluid can be, for example, the fluid to be pumped, which is preferably taken from the high-pressure outlet 4 and / or from the high-pressure area 6b. The rotary pump 1 further comprises a flow guide structure 10, which is arranged in the low-pressure inlet 3. The flow guide structure 10 projects axially from a wall of the pump housing 2 into the low-pressure inlet 3 with respect to the axis of rotation D (compare, for example, Figs. 2, 4-6). The pump housing 2 and the flow guide structure 10 are preferably formed as a single piece, in particular by forming them together. The flow guide structure 10 has a shape that tapers in the opposite direction to the flow of the fluid being pumped. The circumferential width of the flow guide structure 10 increases in the direction of flow of the fluid being pumped. The flow guide structure 10 is arranged in the low-pressure inlet 3 such that it extends axially alongside the conveying area 6, particularly alongside the low-pressure area 6a. In the radial direction, the flow guide structure 10 overlaps at least partially with the conveying area 6. In alternative embodiments not shown in the figures, a section of the flow guide structure 10 that does not radially overlap with the conveying area 6 could extend axially through the entire low-pressure inlet 3 and, for example, divide it. Independently of this, it is also conceivable that the section of the flow guide structure 10 that does not radially overlap with the conveying area 6 extends axially over less than 75%, preferably less than 50%, of the axial extent of the conveying area 6, particularly the low-pressure area 6a. The fluid flowing in the low-pressure inlet 3 approaches the flow guide structure 10 from a radial and / or tangential direction with respect to the axis of rotation D. The flow guide structure 10 is preferably not approached from an axial direction. The flow guide structure 10 is designed to influence the fluid flow, or at least a portion thereof, flowing in the low-pressure inlet 3, in particular to change its direction. This means, for example, that a first partial flow of the fluid is influenced or deflected by the flow guide structure 10 in such a way that the first partial flow acquires at least one flow direction component that is opposite to the direction of rotation of the conveying rotor 5. A second partial flow of the fluid is influenced or deflected by the flow guide structure 10 in such a way that...deflected so that the second partial flow receives at least one flow direction component that corresponds to the direction of rotation of the conveying rotor 5. The flow-guiding structure 10 comprises a leading edge 14. The leading edge 14 forms a kind of profile nose or leading edge of the flow-guiding structure 10. In other words, the leading edge 14 is an edge facing the fluid flowing in the low-pressure inlet 3, which the fluid first encounters when it flows towards the flow-guiding structure 10 in the low-pressure inlet 3. Preferably, the stagnation point of the flow-guiding structure 10 is located on the outer circumference of the leading edge 14. Independently of this, the leading edge 14 is spaced radially away from the conveying area 6, in particular from the low-pressure area 6a. The fluid flowing in the low-pressure inlet 3 approaches the leading edge 14 from a radial and / or tangential direction with respect to the axis of rotation D. Preferably, the flow does not approach the leading edge 14 from an axial direction. The flow guide structure 10 comprises a first side wall 11. The first side wall 11 projects axially into the low-pressure inlet 3. Advantageously, the first side wall 11 extends from the leading edge 14 into the radial overlap with the conveying area 6. The first side wall 11 has a minimum distance to the axis of rotation D, which essentially corresponds to the radius of the outer surface 5c of the rotor body 5b. The fluid flowing along the first side wall 11 is influenced by the first side wall 11 in a direction-changing effect. In particular, the fluid flowing past the first side wall 11 is directed in a direction opposite to the direction of rotation of the conveying rotor 5. One wall of the pump housing 2, facing the first side wall 11 and opposite the first side wall 11, forms a first partial inlet channel 3b together with the first side wall 11. The first partial inlet channel 3b is an axially open channel on one side in the low-pressure inlet 3. A partial flow of the fluid flowing in the low-pressure inlet 3, flowing in the first partial inlet channel 3b, is directed in the first partial inlet channel 3b in a direction opposite to the direction of rotation of the conveying rotor 5. The flow guide structure 10 comprises a second side wall 12. The second side wall 12 projects axially into the low-pressure inlet 3. Advantageously, the second side wall 12 extends from the leading edge 14 into the radial overlap with the conveying area 6. The second side wall 12 has a minimum distance to the axis of rotation D, which essentially corresponds to the radius of the outer surface 5c of the rotor body 5b. The fluid flowing along the second side wall 12 is influenced by the second side wall 12 in a direction-changing effect. In particular, the fluid flowing past the second side wall 12 is directed in a direction corresponding to the direction of rotation of the conveying rotor 5. One wall of the pump housing 2, facing the second side wall 12, forms a second partial inlet channel 3c together with the second side wall 12. The second partial inlet channel 3c is an axially open channel in the low-pressure inlet 3. A partial flow of the fluid flowing in the low-pressure inlet 3, flowing in the second partial inlet channel 3c, is directed in the second partial inlet channel 3c in a direction corresponding to the direction of rotation of the conveying rotor 5. The flow-guiding structure 10 comprises an axial end wall 13. The axial end wall 13, the detailed shape of which is described in more detail below and with reference to Figures 4, 5 to 6, connects the first side wall 11 with the second side wall 12 in the circumferential direction. Advantageously, the axial end wall 13 extends from the leading edge 14 into the radial overlap with the conveying area 6. For better understanding, the sectional view of the rotary pump 1 shown in Fig. 1 is shown in perspective in Fig. 2. For an explanation of the construction and operation of the rotary pump 1 shown in Fig. 2, please refer to the above explanations. Fig. 3 shows a second sectional view of the embodiment shown in Fig. 1. The perspective of the second sectional view shown in Fig. 3 corresponds to the perspective in Fig. 1. In contrast to Fig. 1, the actuating element 20, the conveying rotor 5 and the restoring device 8 have been hidden in Fig. 3. The representation in Fig. 3 reveals an end face 2a of the pump housing 2. The outer circumference of the end face 2a has the same radius with respect to the axis of rotation D as the outer surface 5c of the rotor body 5b, which is not shown in Fig. 3. In alternative embodiments, for example, if the rotary pump 1 is designed as an internal gear pump 1, the outer circumference of the end face 2a with respect to the axis of rotation D can have the same radius as the root radius of the internal gear. In the embodiment shown in Fig. 3, the first and second side walls 11, 12 extend radially to the outer circumference of the end face 2a. The circumferential distance between the first side wall 11 and the second side wall 12 increases towards the outer circumference of the end face 2a. Fig. 3 has been supplemented by a skeleton line 17 of the flow-guiding structure 10 (also called flow-guiding structure centerline 17). The skeleton line 17 extends from the leading edge 14 in the flow direction to the outer circumference of the frontal surface 2a. Independently of this, the skeleton line 17 has a curvature in the radial direction. In particular, the skeleton line 17 curves from radially inward to radially outward in the direction of the fluid connection 3a of the low-pressure inlet 3. As shown in the embodiment, the first partial inlet channel 3b tapers in the flow direction. In other words, the cross-section of the first partial inlet channel 3b decreases in the flow direction. The first partial inlet channel 3b is nozzle-shaped, so that the flow velocity of the fluid flowing in the first partial inlet channel 3b increases along its length. Independently of this, the second partial inlet channel 3c also tapers in the flow direction. In other words, the cross-section of the second partial inlet channel 3c decreases in the flow direction. The second partial inlet channel 3c is nozzle-shaped, so that the flow velocity of the fluid flowing in the second partial inlet channel 3c increases along its length. The flow guide structure 10 has the shape of a shark fin in the axial view, which is concavely indented in the course of the first side wall 11, which faces the inflowing fluid, and convexly bulged in the course of the second side wall 12 in order to guide the fluid in a flow-friendly manner towards the conveying area 6. Figures 4 and 5 show a third and fourth sectional view of the embodiment of the rotary pump 1 shown in Figure 1. In the third and fourth sectional views, the rotary pump 1 was cut along the axis of rotation D. In contrast to the third sectional view in Figure 4, the section plane of the fourth sectional view (Figure 5) is rotated a few degrees around the axis of rotation D in the direction of rotation of the conveying rotor 5. In the illustrated embodiment of the rotary pump 1, the pump housing 2 is formed in two parts. The pump housing 2 comprises a housing cover 2b and a housing bowl 2c. The housing cover 2b has a first end face 2a, and the housing bowl 2c has a second end face 2a opposite the first end face 2a. The pumping rotor 5 is arranged axially between the two end faces 2a. The housing bowl 2c includes the fluid connection 3a of the low-pressure inlet 3. The flow guide structure 10 is also fully formed within the housing bowl 2c. The second end face 2a of the housing bowl 2c defines an imaginary plane (not shown in the figures) that extends orthogonally to the axis of rotation D. As shown in Figures 4 and 5, the flow guide structure 10 comprises a first section 15, which radially overlaps the conveying area 6, in particular the low-pressure area 6a. The axial end wall 13 has an orthogonal distance to the imaginary plane, which is at least partially constant in the first section. Independently of this, the axial end wall 13 transitions into the second end surface 2a in the first section 15, particularly in the region of the outer circumference of the second end surface 2a. The flow guide structure 10 comprises a second section 16. The second section 16 adjoins the first section 15 in a radial direction, radially outward with respect to the axis of rotation D. In other words, the second section 16 is arranged immediately adjacent to the first section 15, opposite to the flow direction. The second section 16 does not radially overlap with the conveying area 6. Independently of this, the second section 16 includes the leading edge 14. The orthogonal distance between the axial end wall 13 and the imaginary plane varies in the second section 16. In the region of the leading edge 14, the axial end wall 13 has a maximum orthogonal distance to the imaginary plane. In the flow direction and / or from radially outward to radially inward, the orthogonal distance between the axial end wall 13 and the imaginary plane decreases.In the second section 16, the axial end wall 13 has a concave surface shape with respect to the imaginary plane. As can be seen in Fig. 5, the flow guide structure 10 forms a ramp 18 on its free upper surface, i.e., on the end face 13, which rises towards the actuating element 20. The ramp 18 can be formed, in particular, in the region of section 16. Fluid flowing over the ramp 18 acquires an axial directional component due to the ramp 18, so that, in line with the ramp 18, it also flows with an axial directional component into the conveying cells 7 passing through the low-pressure region 6a. Fig. 6 shows a section of a side view of the embodiment of the rotary pump 1 shown in Fig. 1. In Fig. 6, the viewer has a perspective view into the fluid connection 3a of the low-pressure inlet 3. The second section 16 of the flow guide structure 10 is particularly visible. For details regarding the specific design of the flow guide structure 10, please refer to the above descriptions. Reference symbol: 1 Rotary pump 2 Pump housing 2a End face 2b Housing cover 2c Housing bowl 3 Low-pressure inlet 3a Fluid connection 3b First partial inlet channel 3c Second partial inlet channel 4 High-pressure outlet 5 Pumping rotor 5a Pumped medium 5b Rotor body 5c Outer surface of the rotor body 6 Pumping range 6a Low-pressure range 6b High-pressure range 7 Pumping cells 8 Restoring element 9 - 10 Flow guide structure 11 First side wall 12 Second side wall 13 Axial end wall 14 Leading edge 15 First section 16 Second section 17 Skeleton line 18 Ramp 19 - 20 Actuator 21 Inner surface of the actuator 22 Pressure channel 23 Pressure chamber D Axis of rotation of the pumping rotor

Claims

Rotary pump (1) for pumping a fluid, the rotary pump (1) comprising (a) a pump housing (2) with a low-pressure inlet (3) and a high-pressure outlet (4) for the fluid to be pumped, (b) a pumping rotor (5) rotatably arranged in the pump housing (3) about an axis of rotation (D) with (c) several pumping means (5a) distributed around the circumference of the pumping rotor (5) for pumping the fluid from the low-pressure inlet (3) to the high-pressure outlet (4), wherein (d) the pumping means (5a) with their radial and axial outer edges define a pumping area (6) of the rotary pump (1) when the pumping rotor (5) is rotated, and (e) the rotary pump (1) has a flow guide structure (10) projecting axially into the low-pressure inlet (3) with respect to the axis of rotation (D), which is designed to influence, preferably to change the direction of, the fluid flowing in the low-pressure inlet (3),wherein (f) the flow guide structure (10) is arranged axially next to the conveying area (6) and overlaps at least section by section with the conveying area (6) in the radial direction, and wherein (g) the flow guide structure (10) has a leading edge (14) which is spaced radially away from the conveying area (6) and is arranged substantially parallel to the axis of rotation D. Rotary pump (1) according to the preceding claim, wherein the width of the flow guide structure (10) is limited in the circumferential direction by two side walls (11, 12), and the width of the flow guide structure (10) measured in the circumferential direction increases in the flow direction of the fluid to be pumped. Rotary pump (1) according to the preceding claim, wherein the side walls (11, 12) extend in a radial direction from the leading edge (14) to the radial overlap with the conveying area (6). Rotary pump (1) according to one of claims 2 or 3, wherein a maximum distance measured in the circumferential direction between the two side walls (11, 12) is greater than a maximum distance measured in the circumferential direction between two adjacent conveying means (5a) and / or the maximum distance measured in the circumferential direction between the two side walls (11, 12) is less than a maximum distance measured in the circumferential direction between the two outer conveying means (5a) of a total of three adjacent conveying means (5a). Rotary pump (1) according to one of the preceding claims, wherein a first side wall (11) of the flow guide structure (10) together with the wall of the low-pressure inlet (3) forms a first axially one-sided open partial inlet channel (3b), and the fluid flowing through the first partial inlet channel (3b) is directed in a direction opposite to the direction of rotation of the conveying rotor (5). Rotary pump (1) according to one of the preceding claims, wherein a second side wall (12) of the flow guide structure (10) together with the wall of the low-pressure inlet (3) forms a second axially open partial inlet channel (3c), and the fluid flowing through the second partial inlet channel (13) is directed in a direction corresponding to the direction of rotation of the pump rotor. Rotary pump (1) according to one of the preceding claims, wherein the first partial inlet channel (3b) according to claim 5 and / or the second partial inlet channel (3c) according to claim 6 has / have a cross-section that tapers in the direction of flow. Rotary pump (1) according to one of the preceding claims, wherein the flow guide structure (10) is axially limited by an axial end wall (13) which is at least partially concave and / or convex. Rotary pump (1) according to claim 8, wherein the flow guide structure (10) comprises a first section (15) which overlaps in the radial direction with the conveying area (6), wherein the axial end wall (13) in the first section (15) has a minimum axial distance to the conveying area (6). Rotary pump (1) according to claim 8 or 9, wherein the flow guide structure (10) comprises a second section (16) which is provided radially next to the pumping area (6), wherein the axial end wall (13) in the second section (16) is at least partially concave and / or convex. Rotary pump (1) according to one of the preceding claims, wherein a skeleton line (17) of the flow guide structure (10) has a curvature in the radial direction. Rotary pump (1) according to one of the preceding claims, wherein the flow guide structure (10) is arranged in the low-pressure inlet (3) such that the flow guide structure (10) is exposed to the fluid flowing in the low-pressure inlet (3) from a radial and / or tangential direction with respect to the axis of rotation (D). Rotary pump (1) according to one of the preceding claims, wherein the low-pressure inlet (3) extends from a fluid connection (3a) on the outer wall of the pump housing (2) to the delivery area (6), preferably in a radial and / or tangential direction to the delivery area (6). Rotary pump (1) according to one of the preceding claims, wherein the rotary pump (1) is a vane pump (1) or a gear pump, in particular an internal gear pump.

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